Light Based Projectile Detection System for a Virtual Firearms Training Simulator

ABSTRACT

A light based projectile detection system for use with a firearm and a virtual firearms training simulator includes a self-sealing screen having a proximal side and a distal side. A scenario projector transmits a simulation onto the proximal side, and a light source faces the distal side. The light source selectively projects light onto the distal side of the screen when the firearm is shot, such that light from the source traverses the screen after contact by a projectile. A camera monitors the light traversing the aperture created by the projectile to determine and associate the position of impact and transmit that information to a scenario computer. The system may include an audio detection circuit to monitor the sound generated by the firearm and transmit a signal to a flash controller to cause the light source to illuminate. The screen will then re-seal around the hole so that the light no longer traverses the screen.

CROSS REFERENCE TO RELATED PATENT APPLICATIONS

This application claims priority from co-pending U.S. Provisional Application Ser. No. 61/162,498, filed on Mar. 23, 2009, said application being relied upon and incorporated herein by reference.

FIELD OF INVENTION

The present invention relates to a system and method for determining the actual coordinates of a projectile impact in a screen and associating the point of impact with a firearms training simulation.

BACKGROUND OF THE INVENTION

A typical virtual firearms training simulator uses simulated weapons that do not fire real bullets to train students on the proper handling of a weapon during a simulated real life scenario. The training scenario includes a video, digital animation, or other virtual scenario of one or more situations requiring the user to react quickly and decisively, such as a hostage scenario, terrorist attack, or general malfeasance. This scenario is projected onto a screen using a video projector, with the scenario being controlled by a simulation computer that also detects the point of aim at the instance the student pulls the trigger of the simulated weapon. The simulated weapon is equipped with either an invisible or visible laser that “fires” a laser pulse when the trigger is pulled. A camera, in electrical communication with the simulation computer, detects this pulse of light, and transmits the impact coordinates to the simulation computer. The simulation computer then determines the location of the hit relative to the scenario being broadcast by matching the coordinate system of the camera to the coordinate system of the projected image or target.

A drawback to this system is that the simulated weapon operated by the user often simply generates a laser pulse to imitate the firing of the weapon, which does not produce a realistic experience for the user. That is, the simulated weapon typically does not have the feel of an actual firearm, and often does not produce recoil action, or produces unrealistic recoil action for the user, such that the simulation lacks credibility for the user. Consequently, trainees that are not used to extensive target practice with live firearms may be disadvantaged when required to handle firearms in combat situations.

A variant of this virtual firearms training simulator is one that detects real bullets fired from an actual live weapon. Since a bullet is not a pulse of light, the camera detection method described above may not seem practical to use. Rather, several alternative detection methods have been developed as an add-on to an existing simulator's laser detection system. They include detection of the visual image of the bullet as it passes an array of sensors, detection of the heat signature of the bullet as it penetrates the screen, detection of the acoustical waves generated by the bullet as it passes an array of acoustic sensors, or detection of the hole that the bullet makes when penetrating a screen material such as paper. While all of these methods may work to some degree, none of them are performed within desired parameters, such as at a low financial cost and having a high degree of accuracy.

BRIEF SUMMARY OF THE INVENTION

A light based projectile detection system for a firearm and a virtual firearms training simulator is described herein. The light based projectile detection system includes a self-sealing screen having a proximal side and a distal side. A scenario projector transmits a simulation onto the proximal side, and a light source (such as a flash) faces the distal side. The light source selectively projects light onto the distal side of the screen when the firearm is shot, such that light from the source traverses the screen after contact by a projectile. A camera monitors the light traversing the aperture created by the projectile to determine and associate the position of impact and transmit that information to a scenario computer.

The system may include an audio detection circuit to monitor the sound generated by the firearm and transmit a signal to a flash controller to cause the light source to illuminate. The screen will then re-seal around the hole so that the light no longer traverses the screen.

The system may additionally include a housing to support the screen, with the light source surrounded by the housing and screen to control the distribution of light from said light source. In such an embodiment, a reflective panel (such as paper with foil on one side) may be mounted in said housing diagonally, with the light source positioned between the reflective panel and the screen. This arrangement will project light directly onto the distal side of the screen as well as onto the reflector panel, which will assist in evenly projecting light on the distal side of the screen.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of the light based projectile detection system for a virtual firearms training simulator;

FIG. 2 is a second block diagram of the light based projectile detection system for a virtual firearms training simulator of FIG. 1, the diagram showing the impact of a projectile with a screen; and

FIG. 3 is a perspective view of the screen and light assembly incorporated into the system illustrated in FIGS. 1 and 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1-3, a light based projectile detection system 10 is illustrated. The light based projectile detection system 10 is able to monitor the impact of a projectile 18 fired by an actual firearm 16 on a self-sealing screen 14 using a laser detection system 12 similar to those described above and as used in a typical laser-based virtual firearms training simulator known in the art.

More specifically, the laser detection system 12 includes a scenario projector 20 and a camera 22 that are both in electrical communication with a simulation or hit detect computer 24. The projector 20 may include any type of image-generating device, and receives a simulation scenario from the hit detect computer 24. The projector 20 will then broadcast that scenario on one or more self-sealing screens 14. In contrast, the camera 22 monitors the self-healing screen 14 for a light or laser pulse, which will correspond to the point of impact of the projectile 18 fired in during the simulation projected on the screen 14. That is, the laser detection system 12 will monitor the actual live fire of the weapon 16 to determine the impact position of a fired projectile 18, such as a bullet or slug, through the screen 14 during simulation scenarios projected on the screen 14. Once the light pulse is detected, the camera 22 will transmit the coordinates of the impact to the hit detect computer 24. The computer 24 includes software that will be able to compute the impact coordinate relative to predetermined screen coordinates relative to the projected target.

To leverage the laser detection system 12 to determine the bullet position of impact on the screen 14, the bullet 18 must generate a pulse of light at the specific location L1 where the bullet 18 impacts the screen 14 after being fired by the weapon 16. To generate this pulse of light, the projection screen 14 of the bullet detection system 10 is made of a self-healing elastomeric material, such as a natural gum rubber or other similar substance known in the art. The screen 14 has a proximal side 14 p and an opposite distal side 14 d. The proximal side 14 p faces and is closest to the laser detection system 12, while the distal side 14 d opposite the proximal side 14 p faces and is closest to a light source 26. The light source 26 outputs wavelengths of light 28 that can be detected by the same camera 22.

When a projectile 18 penetrates the surface of the screen 14 at location L1 (see FIG. 1), it will create a hole H1 at the location L1 that creates a light valve to allow light 28 to travel through the screen 14 (see FIG. 2). After a period of time, the self-healing material of the screen 14 will re-seal the hole H1 so that the camera 22 will no longer monitor any light 28 through the screen 14. As a result, the brief exposure of light 28 through the light valve H1 in the screen 14 will simulate a light pulse. Because the temporary hole H1 is the position L1 of the bullet 18 at impact, the accuracy for monitoring the light through the light valve H1 by the camera 22 is the same as the laser pulse detection (as described above). Any calibration algorithm used by the hit detect computer 24 to match the coordinate system of the camera 22 to the coordinate system of the projected simulation of the hit detect computer 24 as projected by projector 20 may be used in the present system; that is, the calibration algorithm used by the simulation hit detect computer 24 to match the coordinate system of the camera 22 to the coordinate system of the projected simulation of the hit detect computer 24 will remain the same whether one uses a laser pulse in prior simulation systems or shoots a real bullet 18 in the training scenario of the present system.

A prototype of the design integrated with typical virtual small arms training simulator is illustrated in FIG. 1. This prototype was tested for accuracy in matching the contact of the bullet 18 with the scenario, and the results were accurate within 1 to 3 mm, which is very similar to the laser-based system. It was determined the best way to get the most amount of light 28 for the camera 22 to detect the bullet 18 passing through the screen was to use a xenon flash 26 facing the distal side 14 d of the screen 14 that is selectively illuminated instead of a continuous light source. A xenon flash was selected for its desirable properties in light intensity while generating relatively lower heat. As a result, a flash triggering system 30 is connected to the light source 26 to ensure proper timing of the light 28 with the firing event of the weapon 16.

The flash triggering system 30 includes an audio detection circuit 32 or other means for generating a signal corresponding to the firing of the firearm 16 in electrical communication with a flash/trigger controller 34. The audio detection circuit 32 may be any known in the art, such as a circuit including a microphone for converting audio energy (sound waves) into an electrical signal. Other sensors or means for generating a signal corresponding to the firing of the firearm 16 may be incorporated in the system 30 to monitor the operation of the firearm 16. Such sensors include, but are not limited to, a photocell sensor for monitoring the muzzle flash of the bullet 18 leaving the firearm 16 or a sensor for measuring the vibration of the firearm 16 (such as an accelerometer or a piezoelectric sensor) when fired. Thus, the flash triggering system 30 is able to monitor any element associated with the firing of the firearm 16 (sound, vibration, light, or other features associated with the operation of the firearm 16) to generate a desired signal to transmit to the controller 34 upon the firing of the weapon 16. Similarly, the flash/trigger controller 34 may be a conventional microcontroller that is in electrical communication with the audio detection circuit 32 and the light source 26. In the illustrated embodiment, the audio detection circuit 32 is positioned somewhat near the weapon 16, and detects the sound associated when the weapon 16 is initially shot. The audio detection circuit 32 thereby transmits a signal to the flash controller 34 corresponding to the timing of the weapon 16 being fired.

The flash controller 34, which is in electrical communication with the light source 26, will use the signal transmitted from the audio detection circuit 32 to further send a signal triggering a bank of facing the distal side 14 d of the screen 14. The xenon flash bulbs 26 will therefore be illuminated at the approximate time when the bullet 18 penetrates through the self-healing rubber front surface 14 p. This is accomplished by having the controller 34 turn the flash bulbs 26 on after a pre-determined time delay to ensure the camera 22 will detect or view the light 28 while there is a bullet hole H1 in the screen 14. This time delay will vary depending on the speed of the bullet 18 used and the distance that the firearm 16 is from the screen 14.

Looking to FIG. 3, the screen 14 may be mounted in a housing or frame 36 (one side of the housing 36 is removed to view the screen 14). The housing 36 and screen 14 define a casing that surrounds the light source 26, such that the housing 36 and screen 14 will contain all light produced by light source 26 until the screen 14 is pierced by a bullet 18. Although the present rectangular housing 36 is illustrated, other frames may be implemented for the housing 36 as desired by the user. Furthermore, a reflector panel 38 may be diagonally mounted within the housing 36 above the light source 26, such that the light source 26 is positioned between the reflector panel 38 and the screen 14. The reflector panel 38 may be made of a sheet of paper with foil on a side nearest the light source 26 or some other similar material that has a high reflectivity to effectively reflect and distribute the light produced by the light source 26. The light source 26 will therefore project light directly onto the screen 14 as well as onto the reflector panel 38 to project light evenly on the distal side 14 d of the screen 14.

As noted above, a prototype using xenon flash bulbs 26 was developed and tested to work as expected with accuracy to be within 1 to 3 mm.

Without knowing the properties of the rubber screen 14 (such as the stretch or hardness), an assumption is made that there is a finite amount of time before the screen 14 will re-seal itself (return back to its original shape) depending on the distance and failure point of the stretch in the screen 14. A further assumption of a worst case condition is that the re-seal time is zero (that is, that the screen 14 is a perfect material that reseals instantly). In other words, the screen 14 is sealed as soon as the bullet or slug 18 passes through the screen 14. It is also assumed that the only time “light” 28 is allowed through the screen 14 is while the slug 18 is penetrating the screen 18 (i.e., the initial hole H1 that the slug 18 makes is bigger than the slug 18 to allow this light 28 to come through as the slug 18 is passing through.) To determine how much light 28 is directly related to the speed of the slug 18 and how long the “light valve” is left on (that is, how long light passes through the screen 14 before it reseals), the following equation should be used:

Light valve on time=[(length of slug+thickness of screen+distance the screen stretch before initial penetration)/speed of slug]+[resealing time once the slug 18 passes], the following measurements are determined.

Assuming that the minimum distance of stretch in the screen 14 is half of the diameter of the slug 18 (but is most likely more) and is dependant of speed of the slug 18 and material property of the screen 14, 5 mm as the screen thickness, 0 sec for the resealing time once the slug passes (this is somewhat dependant on how far the material is stretched and the screen material property), the following calculations are made:

A typical spec for a 9 mm NATO ball is: Speed of slug range from 950 ft/s to 1300 ft/s with a slug length of 0.610″ or 15.5 mm.

A typical specification for a 5.56 mm, ball is: Speed of slug is 3250 ft/s with the slug length of 19.3 mm to 23 mm.

So minimum light valve on time for a 9 mm slug is (15.5+5+4.5)/(1300*304.8)=63.1 μsec, and the minimum light valve on time for a 5.56 mm is (19.3+5+2.28)/(3250*304.8)=26.8 μsec.

In a charged coupled device (CCD) in the camera 22 for capturing images, there is a photoactive region (an epitaxial layer of silicon), and a transmission region made out of a shift register. An image is projected by a lens on the capacitor array (the photoactive region), causing each capacitor to accumulate an electric charge proportional to the light intensity at that location. The exposure time for the light valve H1 is calculated at a minimum from 26.8 to 63.1 μsec (based on the calculations for the above-noted assumptions). Consequently, it is possible to detect the charge if the intensity is large enough using the CCD sensor as long as the noise level in the CCD sensor is not larger than the charge. Since this is really an absolute minimum in an ideally perfect situation, the actual time the light valve H1 will be open will be greater, if not significantly greater.

In addition, there is a blanking time between the shifting of data out of the register where the CCD sensor cannot accumulate charges. This blanking needs to be as small as possible. The current camera 22 has about a 2 msec blank time. This is more of a function determined by the camera manufacturer. For example, the current camera 22 being evaluated for the system 10 has a blank time between frames of 35 μsec out of the box and can be adjusted even lower.

The calculations support the theory that the capabilities of CCD sensor can allow it to detect a bullet slug 18 traveling through a re-sealable rubber screen 14 with a back-lit light source 26.

The design above was initially tested using a rubber live fire screen as a proof of concept, some incandescent light bulbs, a standard 100 D-P (small arms virtual system) with the standard hit camera 22 and a filter (an infrared filter used to monitor the desired light) and a TV monitor. The back side or distal side 14 d of the screen 14 was lit using light bulbs totaling approximately 1000 watts, with the rear rubber screen removed so that only the front rubber screen was separating the light 26 and the shooter. The hit camera 22 was pointed on the screen 14 as usual and the TV monitor connected to “see” the output of the hit camera 22. The design was tested with both 9 mm and 5.56 mm rounds 18. In all cases, the users were able to visually see the light 28 come through the screen 14 momentarily before the screen 14 would reseal after the slug 18 passed through.

The 5.56 slug 18 did leave a pinhole and did not completely reseal like the 9 mm slug 18. A small piece of the screen 14 had been torn off from the back or distal side 14 d when the 5.56 mm slug 18 was shot, which did not occur with the 9 mm. A momentary faint blurry light appeared on the TV monitor indicating where the slug 18 went through the screen 14, which showed that detection is possible and, with the right combination of filters, camera, screen material, and lighting source, it is possible to design a system to detect the brief pulse of light 28 caused by the penetration of the bullet slug 18.

A high speed camera was also used to determine the approximate on time of the material (how long the light valve H1 appears to be open) once a 9 mm slug has penetrated the screen 18. The frame rate of the camera was approximately 8000 frames per sec. The hole H1 appeared to be open for at least 4 frames or 4/8000 or 0.5 msec which is more 9 times longer than calculated for the worst case scenario. These test results further demonstrated that the proposed device will operate as desired.

Having thus described exemplary embodiments of a LIGHT BASED PROJECTILE DETECTION SYSTEM FOR A VIRTUAL FIREARMS TRAINING SIMULATOR, it should be noted by those skilled in the art that the within disclosures are exemplary only and that various other alternatives, adaptations, and modifications may be made within the scope of this disclosure. Accordingly, the invention is not limited to the specific embodiments as illustrated herein, but is only limited by the following claims. 

1. A light based projectile detection system for use with a firearm firing a projectile and a virtual firearms training simulator having a scenario projector, a camera, and a scenario computer, said projectile detection system comprising: a self-sealing screen having a proximal side and a distal side, the scenario projector transmitting a simulation onto said proximal side; and a light source facing said distal side of said screen to selectively project light onto said distal side of said screen; wherein light from said light source traverses said self-sealing screen to be monitored by the camera at the point of contact of the projectile with said self-sealing screen.
 2. The projectile detection system as described in claim 1, further comprising: a sensor generating a signal corresponding to the operation of the firearm; and a flash controller in electrical communication with said sensor and said light source to illuminate said light source corresponding to the firing of the firearm.
 3. The projectile detection system as described in claim 1 further comprising a housing supporting said screen, said housing controlling the distribution of light from said light source proximate said screen.
 4. The projectile detection system as described in claim 3 wherein said light source includes a xenon flash.
 5. The projectile detection system as described in claim 3 further comprising a reflective panel mounted in said housing, said light source positioned between said reflective panel and said screen.
 6. A training system to detect impact coordinates of one or more projectiles fired by one or more firearms, the system comprising: a self-sealing screen having a proximal side and a distal side; a light source facing said distal side of said screen to selectively project light onto said distal side of said screen; a simulation computer generating a simulation; a projector in electrical communication with said computer, said projector broadcasting a simulation on said proximal side of said screen; a camera in electrical communication with said computer to detect a light pulse on said screen; wherein light from said light source traverses said self-sealing screen to be monitored by said camera at the point of contact of the projectile with said self-sealing screen upon impact of the projectile through said screen.
 7. The training system as described in claim 6 further comprising: means for generating a signal corresponding to the firing of the firearm; and means for controlling the illumination of said light source corresponding to said signal.
 8. The training system as described in claim 7 wherein said signal generating means comprises an audio detection circuit positioned proximate the firearm, said audio detection circuit including a microphone to monitor the sound of the firing of the firearm.
 9. The training system as described in claim 7 wherein said control means comprises a flash controller in electrical communication with said audio detection circuit and said light source to illuminate said light source corresponding to the signal generated by said audio detection circuit.
 10. The training system as described in claim 7 further comprising a housing supporting said screen, said housing controlling the distribution of light from said light source proximate said screen.
 11. The training system as described in claim 10 further comprising a reflective panel mounted in said housing, said light source positioned between said reflective panel and said screen.
 12. The training system as described in claim 7 wherein said light source comprises a xenon flash.
 13. A method for determining the position of impact on a target of a projectile launched by a firearm, said method comprising the steps of: a) providing a self-sealing screen having a proximal side and a distal side; b) generating the target on the proximal side of said screen using a projector in electrical communication with a simulation computer; c) monitoring the proximal side of the screen for a light pulse with a camera in electrical communication with said simulation computer; d) selectively illuminating said distal side of said screen with a light source; e) generating a light pulse in said screen with said light source when the projectile traverses said screen; and f) registering the point of contact of the projectile with said screen with said camera connected to said simulation computer.
 14. The method as described in claim 13 wherein step d) further comprises the steps of: generating a signal corresponding to the discharge of the projectile from the firearm; and transmitting said signal to said light source to selectively illuminate said distal side of said screen.
 15. The method as described in claim 14 further comprising the step of monitoring the sound of the discharge of the firearm using a audio detection circuit.
 16. The method as described in claim 13 further comprising the step of: supporting said screen and said light source in a housing to control the distribution of light from said light source proximate said screen.
 17. The method as described in claim 16 further comprising the step of: distributing light from said light source along said distal side of said screen with a reflective panel mounted in said housing, said light source positioned between said reflective panel and said screen.
 18. The projectile detection system as described in claim 13 further comprising the step of: providing a xenon flash for said light source.
 19. The projectile detection system as described in claim 2, wherein said sensor comprises an audio detection circuit positioned proximate the firearm, said audio detection circuit having a microphone to monitor the sound of the firing of the firearm. 